1. Field of the Invention
The present invention relates to an electromagnetic actuator drive for adjusting a final controlling element between at least three positions.
2. Description of Related Art
Actuator drives of this type may be used, for example, for actuating a fixed-cycle air valve in the intake tract of an internal combustion engine with the help of which pulsed charging of the internal combustion engine can be achieved. Essentially other applications are also possible in which a final controlling element must be switched between two different switch positions, preferably within very short switching times. For example, use of such an actuator drive for adjusting gas reversing valves in piston engines is conceivable.
German Patent DE 10 2004 037 360 A1 describes an actuator drive of the type defined above, equipped with a soft magnetic armature. This armature is drive-coupled to a final controlling element and has several armature faces. In addition, the actuator drive has several soft magnetic pole elements, each having multiple pole surfaces against which the armature faces come to rest in two end positions of the armature. Furthermore, a restoring device is also provided, driving the armature by spring force into a starting position between the two end positions. With the help of a holding device, the armature can be secured in its end positions by electromagnetic forces.
With the known actuator drive, a joint electromagnetic coil is assigned to all the pole elements; the electromagnetic forces required for securing the armature in its end positions can be generated with the help of this electromagnetic coil. By using just one single coil, the known actuator drive forms a relatively compact and inexpensive design.